Description:

Phages infecting human-associated Bacteroides fragilis (GB-124 phages) have been employed in the European Union (EU) to identify human fecal pollution, but their utility for U.S. was unclear. Primary sewage effluent samples were collected seasonally from seven wastewater treatment plants (WWTP) across the continental U.S., and more time intensive sampling was conducted at local WWTPs, all assayed for plaque forming units (PFU) of GB-124 phages, somatic and FRNA-specific coliphages, as well as adenoviruses (by quantitative PCR [qPCR]). Animal fecal samples (> 250) from 14 different species were tested for the presence of the three phage groups. GB-124 phages were consistently detected in sewage [10-102 PFU mL-1], but not in animal feces. While density estimates of both coliphages in sewage were approximately one order of magnitude higher than GB-124 phages, they were both randomly detected in animal fecal samples (102 to 105 g-1 dry weight). Stability of all three phage groups was inversely proportional to temperature; persistence was greatest at 5 °C compared to 20 & 35 °C where no phages were detectable after a week. In summary, GB-124 phages appear to be a feasible alternative indicator organism with the additional benefit of being sewage-associated, while providing an inexpensive detection technique of infectious virions.

Purpose/Objective:

This research investigated applicability of GB-124 phage to detect human pollution sources in the U.S.